The final step in the assembly of an enveloped virus assembly requires separation of budding particles from the cellular membranes. Three distinct functional domains in Gag, i.e., PTAP in HIV-1 [SEQ ID NO.: 19](Gottlinger et al., 1991. Proc Natl Acad Sci USA 88, 3195-9; Huang et al., 1995, J Virol 69, 6810-8); PPPY in RSV [SEQ ID NO.: 20] (Parent et al. 1995, J Virol 69, 5455-60), MuLV (Yuan et al., 1999, Embo J 18, 4700-10), and M-PMV (Yasuda et al., 1998, J Virol 72, 4095-103); and YXXL in EIAV [SEQ ID NO.: 21] (Puffer et al., 1997, J Virol 71, 6541-6), have been identified in different retroviruses that are required for this function and have been termed late, or L domains (Wills et al., 1991, Aids 5, 639-54). In HIV-1, the L domain contains a PTAP motif and is required for efficient HIV-1 release (see, e.g., Wills et al., 1994, J. Virol. 68, 6605-6618; Gottlinger et al., 1991, Proc. Natl. Acad. Sci. USA 88, 3195-3199; Huang et al., 1995, J. Virol. 69, 6810-6818). The L domain of HIV-1 p6, especially the PTAP motif, binds to the cellular protein TSG101 and recruits it to the site of virus assembly to promote virus budding (VerPlank et al., 2001, Proc. Natl. Acad. Sci. USA 98:7724-7729; Garrus et al., 2001, Cell 107:55-65; Martin-Serrano et. al., 2001, Nature Medicine 7:1313-19; Pornillos et al., 2002, EMBO J. 21:2397-2406; Demirov et al., 2002, Proc. Natl. Acad. Sci. USA 99:955-960; PCT Publication WO 02/072790; U.S. Patent Application Publication No. US 2002/0177207). The UEV domain of TSG101 binds the PTAP motif and mono-ubiquitin (Pornillos et al., 2002, Embo J 21, 2397-406; Pornillos et al., 2002, Nat Struct Biol 9, 812-7), which has also been implicated in HIV-1 budding (Patnaik et al., 2000, Proc Natl Acad Sci USA 97, 13069-74; Schubert et al., 2000, Proc Natl Acad Sci USA 97, 13057-62; Strack et al., 2000, Proc Natl Acad Sci USA 97, 13063-8). Depletion of cellular TSG101 (Garrus et al., 2001, Cell 107:55-65) or over-expression of a truncated form of TSG101 inhibits HIV-1 release (Demirov et al., 2002, Proc. Natl. Acad. Sci. USA 99:955-960). Under certain circumstances, TSG101 can even substitute for the HIV-1 L domain to promote virus release (Martin-Serrano et. al., 2001, Nature Medicine 7:1313-19). Antibodies targeting TSG101 have been shown to inhibit viral release (Li, U.S. Provisional Patent Application No. 60/425,299, filed Oct. 1, 2002).
TSG101 plays important roles in cell growth (Zhong et al., 1998, Cancer Res 58, 2699-702; Oh et al., 2002, Proc Natl Acad Sci USA 99, 5430-5; Krempler et al., 2002, J Biol Chem 277, 43216-23; Wagner et al., 2003, Mol Cell Biol 23, 150-62; Li et al., 1996, Cell 85, 319-29), cellular protein trafficking (Babst et al., 2000, Traffic 1, 248-58; Bishop et al., 2002, J Cell Biol 157, 91-101), and degradation of p53 (Li et al., 2001, Proc Natl Acad Sci USA 98, 1619-24; Ruland et al., 2001, Proc Natl Acad Sci USA 98, 1859-64; Moyret-Lalle et al., 2001, Cancer Res 61, 486-8). In yeast, the Tsg101 ortholog Vps23 has been shown to interact with Vps28 and Vps37 and to form a protein complex named ESCRT-I, which is critical for endosomal protein sorting into the multivesicular body pathway (Katzmann et al., 2001, Cell 106, 145-55). It is hypothesized that this intracellular multivesicular body formation resembles HIV-1 release at the plasma membrane (Garrus et al., 2001, Cell 107:55-65; Patnaik et al., 2000, Proc Natl Acad Sci USA 97, 13069-74). In mammalian cells, TSG101 interacts with Vps28 to form an ESCRT-I-like complex (Babst et al., 2000, Traffic 1, 248-58; Bishop et al., 2002, J Cell Biol 157, 91-101; Bishop et al., 2001, J Biol Chem 276, 11735-42), although the mammalian homolog of Vps37 has not been identified.
Citation of references herein shall not be construed as an admission that such references are prior art to the present invention.